The Black Berkey micron rating needs to be defined in both micron and log rating, log rating between 4 -9 log 99.99% to 99.9999999% for viruses and bacteria, please visit Berkey Knowledge for more detailed lab reports. 

Below is an extract from Berkey Knowledge Base

With respect to the micron rating, NMCL does not use or publish a micron rating for the Black Berkey® elements for the following reasons:

There is much confusion with respect to nominal and absolute micron ratings. An absolute micron rating is one that states the maximum pore size expected within an element. The nominal micron rating is the average pore size within the element. This means that if 90% of the pores are .02 microns and ten percent are 2 microns, one could claim the nominal micron rating as .2 microns, which would imply that pathogenic bacteria and parasites would be totally removed. But in reality the bulk of the water would channel through the larger 2-micron pores and thereby allow both bacteria and parasites to pass through. Therefore a nominal micron-rating claim can be very misleading.

With respect to the absolute micron rating, there is also confusion because there are two different standards to determine absolute; in the US the standard is 99.9% removal, but the international standard in 99.99% removal or 10 times greater removal.

Clever marketers of products can use the confusion over the above differences to make product “A” appear to be better than product “B” when product B may be far superior in reality. For example, we used to report an absolute rating using the international standard because we have a large international customer base. Several years ago we published a rating on our ceramic filters. A particular company began to publish that our elements were .9 microns whereas theirs were .2 microns. However, our micron rating was based on absolute (international) while theirs was based on a nominal (US) rating. When tested at Spectrum Labs, it was found that at the .2 to .3 microns range our filter removed more particulate than the other brand. Unfortunately many people make their purchasing decisions based on a micron rating that can be legitimately distorted and to a significant degree.

Based on the information above, we decided not to participate any longer in publishing a micron rating. Rather, we think an absolute pathogenic bacteria removal rate is a far better gauge because it is far more difficult to abuse. Based on that criterion, the Black Berkey® Purification Elements remove greater than 99.9999999% of pathogenic bacteria such as E.Coli. To our knowledge, no other personal filtration element can match that capability.

More Info

The Black Berkey Purification Elements are made in the USA by New Millennium Concepts who is the manufacturer of Berkey Water filter systems and accessories. These are designed to sit in the top chamber. These are made from coconut husk and a 6 proprietary blend that makes them unique and have the following benefits:

  • Designed to exceed the Purification Class. The Black Berkey Purification Elements filter out more contaminants than elements in the Filtration class which includes White Ceramic Supersterasyl Filtration Elements and Berkey Earth Filtration Elements.
  • Have an Absolute filtration rating (defined as >99.9999999%), equivalent to better than 0.1 micron, Laboratory results reported as small as 24 nm (nanometer = .024 micron)
  • Made from natural coconut husk.  They do not add anything to the water being filtered and the natural healthy minerals remain.  
  • More powerful than any other gravity filter element currently available.
  • They are called "Purification" elements because they are more powerful than filters in the "Filtration" classification and are therefore in the next, higher level of classification.
  • Rated to 11,300 litres or when cleaning is ineffective. Generally last 3-5 years and often longer. Some users have reported 10 years or more.

They can remove: 

  • Pathogenic Bacteria such as E-coli, Salmonella, Legionella, Cholera, Salmonella Typhi (Typhoid), Shigella, Klebsiella >99.9999%
  • Viruses; >99.999% Log 6
  • >99.99% Log 4 ; Cryptosporidium, Giardia, and other cysts
  • Chlorine (taste & odour); below lab detectable levels
  • Rust, Silt and dirt; below lab detectable levels
  • Lead; below lab detectable levels
  • Trihalomethanes - Removed to >99.8% 
  • Chromium: 99.9%

They have some disadvantages such as:

  • Higher cost price. (2 per set)
  • Due to the incredibly small pore size they must be 'primed' before use.

Black Berkey Purification Elements remove or reduce: 

  • Bad odors and taste, transforms municipal mains water into water that tastes sweet and pure  
  • Chlorine to below lab detectable levels 
  • Detergents 
  • Reduces PFOA & PFOS greater than >99.9% 
  • Viruses:  Removed to >99.999% (Log 5) MS2 Coliphage - Fr Coliphage *Exceeds purification standards (Log 4)    
  • Parasites, Protozoa greater than >99.999% (Log 5) giardia, cryptosporidium   
  • Pathogenic Bacteria (And Surrogates): Removed to >99.9999%  (Log 6) Raoultella terrigena (Pathogenic Bacteria Surrogate); Bacillus atrophaues (Anthrax Surrogate); Salmonella Enterica  *Exceeds purification standard (Log 6) 
  • Inorganic Minerals Chloramine; Chloride; Chlorine Residual (Total Residual Chlorine); Free Chlorine  *Removed to Below Lab Detectable Limits 
  • Heavy Metals (High & Low pH Levels) Aluminum (>99%); Antimony (>99.9%); Barium (>80%); Beryllium (>99.9%); Bismuth (>99.9%); Cadmium (>99.7%); Cobalt (>95%); Chromium (>99.9%); Chromium 6 (>99.85%); Copper (>99.9%); Iron (>99.9%); Lead (>99.9%); Mercury (>99.9%); Molybdenum (>90%); Nickel (>99.9%); Vanadium (>87.5%); Zinc (>99.9%)
  • Trihalomethanes: Removed to >99.8% Bromodichloromethane; Bromoform; Chloroform: Dibromochloromethane (Below Lab Detectable Limits):
  • Micro-Organisms:  Removed to >99.9%  Including:  Total Coliform, Fecal Coliform, e.Coli
  • Pharmaceutical Drug Contaminants:  Removed to >99.9% Acetaminophen; Caffeine; Carbamazepine; Ciprofloxacin HCl; Erythromycin USP; Sulfamethoxazole; Trimethoprim; Bisphenol A; Diclofenac Sodium; 4-para-Nonylphenol; 4-tert-Octylphenol; Primidone; Progestrone; Gemfibrozil; Ibuprofen; Naproxen Sodium; Triclosan.
  • Cloudiness, silt and sediment. You can filter creek, river, tank, fish pond and dam water
  • Herbicides and Pesticides (Removed to Below Lab Detectable Limits)
  • Also; Arsenic (>99.9%); Escherichia coli (E. Coli) (>99.999%); Fluorene (>99.9%); Manganese (>99.9%); MBAS (>96.67%); Nitrites (>95%); PCB’s (>99.9%); Petroleum Products (Gasoline, Diesel, Crude Oil, Kerosene, Mineral Spirits, Refined Oil- All >99.9%); Selenium (>99.9%); Thallium (>99.5%); Rust; Silt; Sediment; Turbidity; Foul Tastes and Odors.

Click on links below for a more in-depth lab results study

      1. Black-Berkey-VOC-Pesticide-THM-HAA5-Removal-Test-Report.pdf
      2. Black-Berkey-Heavy-Metal-MBAS-Chlorine-Turbidity-Removal-Test-Report.pdf
      3. Black-Berkey-Gross-Alpha-Radiologica-Removal-Test-Report.pdf
      4. Black-Berkey_Perfluorinated-Chemical-Removal-Test-Report.pdf
      5. Black-Berkey-Gross-Beta-Radiologica-Removal-Test-Report.pdf
      6. Black-Berkey-Lead-Reduction-Test-Report.pdf
      7. Black-Berkey-Uranium-Radiological-Removal-Test-Report.pdf
      8. Black-Berkey-Virus-Bacteria-Removal-Test-Report.pdf
      9. Black-Berkey-Heavy-Metal-Chemical-VOC-Pharmaceutical-Petrol-Removal-Test-Report.pdf

      Below is some information that might be helpful, with respect to the seasonal Algae Blooms that have affected some water supplies in the past few years and also confirms the contaminant size that the Black Berkey® Purification Elements are able to achieve:

      Extract from NMCL Berkey Knowledge Base

      “…Cyanobacterial cells range in size from 0.5-1 μm to 40 μm in diameter…”

      In other words, it’s a long skinny bacteria. Reference:

      Internet research seems to indicate that Microcystin colonies are even larger, typically on the scale of 50 to over 100 micrometers in size.

      While we have not tested the specific microbes associated with Algae Blooms, we have tested other pathogenic bacteria and two viruses, which are a small fraction of the size of these microbes.

      To understand the difference between the size of pathogenic bacteria and viruses, we suggest the following web link as it will give you a great visual of the difference. The University of Utah Cell Size and Scale Chart:

      Slide the scale at the bottom to see the size of virus vs bacteria vs other potential contaminates and magnify to greater levels.

      Black Berkey® purification elements have been tested to remove both pathogenic bacteria and viruses to greater than the EPA purification standards. This suggests that larger bacteria, such as cyanobacteria, should also be effectively removed. Without test data on that specific microbe however, NMCL does not make that specific claim. Recent research indicates that testing of the Black Berkey® element for reduction of Microcystin microbes would cost over $1.4-Million dollars; most of the cost is associated with purchasing a sufficient quantity of the reagent.

      The MS-2 virus is 24-26 nm in size.

      The Fr Coliphage virus is 25nm in size.

      24 nm (nanometer = .024 micron)

      Cyanobacterial cells range in size from 500-1,000nm to 40,000nm in size.

      In other words, they are much smaller than Cyanobacteria.

      Additionally Microcystins, which are the chemical contaminates resulting from cyanobacteria are an organic chemical. Testing of Black Berkey® elements has demonstrated they are extremely efficient at removing organic chemicals.

      The EPA defines Microcystins as: “…toxins produced by cyanobacteria. Cyanobacteria are also known as blue-green algae and are ubiquitous in surface water when conditions are favorable for growth and formation of algal blooms. Cyanobacteria release toxins upon cell death or lysis. When released, toxins may persist for weeks to months. Toxins of most concern are microcystins. Microcystins take their name from the genera Microcystis. Most microcystins are hepatotoxins (liver toxins). Hepatotoxins are produced by species of the genera Microcystis, Anabena, Nodularia, Oscillatoria among others. Most microcystins areassociated with Microcystis aeruginosa. While the liver is the primary target of microcystins, it is also a skin, eye and throat irritant…”


      Further, the EPA states that: “…The following processes are considered effective for the removal/oxidation of microcystin:…. powdered activated carbon (up to 100% for some microcystins but less so for others), granular activated carbon (time-dependent from 100% near start up to 38 to 73% at 3.5 months…”

      Reference: (Click on the “Treatment Process” tab)

      Finally, the EPA states that: “…Removal of total microcystins, M-LR, and M-LA, in water by granular activated carbon (GAC) can be very effective where the effectiveness is based on the empty bed contact time, the carbon’s age, and possible biodegradation of the toxin. Time-dependent monitoring in a full-scale plant ranged 43 to 60 percent removal for M-LR. Time-dependent monitoring in pilot-scale studies ranged from greater than 99 percent at one month to 73 percent at 3.5 months for M-LR, and from greater than 99 percent at one month to 38 percent at 3.5 months for M-LA…”

      REFERENCE: (Click on the “Treatment Process” Tab, scroll down to “Granular Activated Carbon” and click on the link)

      It is also recommended by several sources that pre-treating the un-filtered water to kill off the algae may be accomplished with plain bleach.

      ” A combination selected from the following processes is used for municipal drinking water treatment worldwide:

      -Pre-chlorination for algae control and arresting biological growth”.


       Therefore, as an additional precaution, if using a source of water that you believe might contain extreme viral and bacteriological contamination (such as Microcystins), it is recommended by the CDC, EPA and other organizations that approximately sixteen drops of plain bleach (sodium hypochlorite) per gallon be added to treat the source water before purifying. This should kill minute pathogens such as viruses in approximately 30 minutes. The disinfectant will then be removed from the treated water entirely, including its odor and taste.

       REFERENCE: -or-

      Based upon the above Internet research, Black Berkey® element microbe and organic chemical removal test data and the information provided by the EPA in their reference material cited above; these all suggest that Berkey® water purification systems should be extremely effective at removing and reducing contaminates resulting from the current algae bloom. NMCL also highly recommends that whenever possible, the cleanest source water available should always be utilized.